The present invention relates to chains, which articulate and slide, such as a chain for a power transmission, a chain for a cable guide, a conveyer chain and the like.
As a means for improving the wear resistance of a chain, which articulates and slides, the prior art discloses lead plating or nickel plating on the surfaces of the components, which form the chain, forming a hardened layer of a metal carbide or a metal nitride, MoS2 baking treatment, and sulfurizing by FeS (see Japanese patent publications No. 3122037 and 3199225).
When surfaces of a part of a chain have been subjected to lead plating or nickel plating, hydrogen generated in pickling in the preceding step or the plating is absorbed into a metal structure of a part of the chain to generate hydrogen brittleness in the formation of a plated film, and mechanical strength of the part is remarkably reduced.
Further, the hardened layer of metal nitride or metal carbide or the like has further excellent wear resistance as compared with a lead plated layer or a nickel plated layer. However, as the requirement of high speed and high load for chains has recently been increased, a further improvement of wear resistance has been required. Further, the baking treatment or the sulfurizing treatment can be applied only to metallic materials and cannot be applied to plastic chain components, which are required by recent trends.
Accordingly, the object of the present invention is to provide a wear-resistance-improved wear resistant chain, which does not generate hydrogen brittleness.
To attain this object, a wear resistant chain is characterized in that a surface of at least one of the components forming the chain is provided with a diamond-like amorphous carbon coating.
Further, a wear resistant chain is characterized in that in addition to the configuration of the wear resistant chain, metallic particles are dispersed in the diamond-like amorphous carbon coating.
The chains of the present invention include all chains which articulate and slide, such as a power transmission chain used in an engine or the like, a conveyor chain used in distributing conveyance, a cable guide chain for protecting and guiding a cable, or similar chains. Further, the invention may be applied to chains made of any material such as metal, resin or others. The diamond-like amorphous carbon (DLC) means a carbon coating film having properties similar to diamond, and the carbon coating film is one of a new material of a hard thin film. However, no DLC has been considered for use as a coating film of a chain until now. The present invention has been made by the discovery of the fact that when a diamond-like amorphous carbon, which has not been considered, is used as a coating film material for a chain, excellent wear resistance is obtained.
Thus, when the present invention has the above-described device coating, the following peculiar effects are obtained.
According to the invention, a localized surface area of at least one of components forming a chain which is subject to the greatest wear, is coated with a diamond-like amorphous carbon coating, whereby the generation of hydrogen brittleness is avoided and wear resistance is improved.
According to an additional aspect of the invention, metallic particles are dispersed in the diamond-like amorphous carbon coating. Accordingly, inner stress of the coating is reduced and adhesive power of the coating to the material of a component of a chain is improved. Further, toughness of the coating is improved and a resulting property of the coated component resisting plastic deformation of the material is also improved. Additionally, since the wear resistant chain has a small wear coefficient, the wear resistance of the chain is further improved and at the same time the flexibility of the chain is improved whereby the occurrence of noise and extraneous sound is decreased.